CN113415885B

CN113415885B - IFAS sewage treatment device and treatment process of upper-layer fixed membrane

Info

Publication number: CN113415885B
Application number: CN202110670084.XA
Authority: CN
Inventors: 李怀正; 栗端鑫; 张�杰
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2021-06-17
Filing date: 2021-06-17
Publication date: 2022-12-13
Anticipated expiration: 2041-06-17
Also published as: CN113415885A

Abstract

The invention relates to an IFAS sewage treatment device and a treatment process of an upper fixed membrane, which comprises an anoxic zone, an IFAS zone and a sedimentation zone which are communicated through a pipeline, wherein anoxic sludge is arranged in the anoxic zone, the anoxic zone is used for receiving sewage to be treated, aerobic sludge is arranged in the IFAS zone, an aeration device is arranged in the aerobic sludge, a filler is arranged at the upper part of the aerobic sludge and forms an upper fixed membrane, and the bottom of the IFAS zone is used for receiving the sewage treated by the anoxic zone; the settling zone is provided with a central cylinder, a water outlet groove and a reflecting plate, the central cylinder is used for receiving the sewage treated by the IFAS zone, the reflecting plate is arranged below the central cylinder and used for separating mud from water, and the water outlet groove is arranged above the settling zone and used for discharging water. Compared with the prior art, the IFAS device developed by the invention has extremely high potential in device optimization as a coupling device of activated sludge and a biological membrane, develops the configuration potential of the IFAS device, and provides a new idea and a new method for treating sewage in villages and small towns.

Description

IFAS sewage treatment device and treatment process of upper-layer fixed membrane

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to an IFAS sewage treatment device and a treatment process of an upper fixed membrane.

Background

By 2016, the town built with domestic sewage treatment facilities accounts for only 28% of the total area of the country, and the villages with domestic sewage treatment facilities account for only 20%. Under the actual condition, the device can be put into use for a long time, really plays a role in sewage treatment, and has a lower proportion. Along with the proposal of the concept of rural toilet modification, the three-format septic tank toilet modification mode gradually occupies the mainstream of rural toilet. The septic tank is usually small in volume and cannot meet the requirement of decomposition treatment of excrement, so that the water quality characteristics of sewage in villages and small towns after toilet modification are more obvious. The small volume causes the low retention time, so that the C/N in the sewage after the toilet is changed is further reduced, and the difficulty is increased for the treatment of the sewage in villages and small towns.

There are two main ways for treating sewage in villages and towns. One is to use the mode and experience of secondary biochemical treatment of the urban sewage treatment plant for reference, miniaturize and simplify the traditional urban sewage treatment process, and apply the process to the sewage treatment of villages and small towns. The technology is mainly a biomembrane method and related technologies, and has the greatest advantages of less sludge discharge and more convenient management and maintenance. However, when low C/N sewage is treated, the carbon source is insufficient, and the extra carbon source needs to be added, so that the operation difficulty is greatly increased, the operation pressure in villages and small towns is increased, and the treatment effect is poor. The second process technology mainly adopts a relatively simple ecological treatment mode, and comprises the technical forms of artificial wetland, oxidation pond, land treatment and the like. The process technology has the advantages of relative simplicity, low energy consumption, simple and convenient maintenance, environmental friendliness and the like, but the treatment efficiency of the technology is low, the unit load is relatively small, and the stably operated process needs a larger available field, namely a larger demand on land resources. In general, no matter which type of treatment process, there is room for improvement in the current context of village and town sewage treatment.

The IFAS process is used as a combined process of an activated sludge process and a biofilm process, has the advantages of the activated sludge process and the biofilm process, can improve the biological treatment efficiency through a coupling effect, does not increase the sludge quantity greatly, has wide application prospect in the field of sewage treatment, and is also very suitable for the current situation that the water environment quality needs to be improved urgently in villages and small towns, but the management and maintenance level is low. At present, aiming at the improvement of the IFAS device, more researches focusing on working conditions such as filling rate, reflux ratio and water inlet mode and the like are carried out, and few contents can be used for further developing the potential of the IFAS configuration.

The IFAS device for village and town sewage treatment is mainly optimized and improved in a mode of being combined with other device processes to improve the treatment effect of the whole device. Chinese patent with application number 202010184080.6 proposes an IFAS-AOAS integrated sewage treatment device and process, and focuses on sewage treatment in villages and small towns. Although the effect of sewage treatment in villages and towns can be improved, improvement is not carried out on the condition of low C/N sewage, the management and maintenance of the coupling process are relatively more complicated, the coupling process is not completely suitable for the current situation of villages and towns, and certain limitation is still provided. Chinese patent with application number 201921653170.4 proposes 'an IFAS-MBR-BST combined sewage treatment device', different process coupling is carried out, improvement and optimization can be carried out aiming at the problems of carbon source utilization and denitrification, the quality and stability of effluent water are improved, however, three groups of process coupling inevitably increase the difficulty of management and maintenance, the occupation and construction cost of land resources are increased, and certain defects still exist for village and town sewage treatment.

Generally, under the background of rural toilet improvement, the optimization of the IFAS device is performed only in a process coupling and stacking mode, and still has great limitation.

Disclosure of Invention

In order to overcome the defects of the existing village and town sewage treatment technology, the invention provides an IFAS sewage treatment device and a treatment process of an upper fixed membrane.

The device and the process provided by the invention can not only correspond to the characteristic of low C/N of the town sewage, but also reduce the occupation of land resources and simplify the operation management program, and are very suitable for village and town areas.

The purpose of the invention can be realized by the following technical scheme:

the invention firstly provides an IFAS sewage treatment device with an upper fixed membrane, which comprises an anoxic zone, an IFAS zone and a sedimentation zone which are communicated through a pipeline, wherein anoxic sludge is arranged in the anoxic zone, the anoxic zone is used for receiving sewage to be treated,

aerobic sludge is arranged in the IFAS zone, an aeration device is arranged in the aerobic sludge, a filler is arranged at the upper part of the aerobic sludge, the filler forms an upper fixed film, and the bottom of the IFAS zone is used for receiving sewage treated by the anoxic zone;

the settling zone is provided with a central cylinder, a water outlet groove and a reflecting plate, the central cylinder is used for receiving sewage treated by the IFAS zone, the reflecting plate is arranged below the central cylinder and used for distributing water uniformly and separating mud from water, and the water outlet groove is arranged above the settling zone and used for discharging water.

In one embodiment of the invention, the sludge generated in the sedimentation zone is returned to the anoxic zone through a return pump and a sludge return pipe, so as to realize a sludge return process.

In one embodiment of the invention, a return water inlet tank for receiving sewage and return sludge is arranged at the upper part of the anoxic zone.

In one embodiment of the invention, an anoxic stirrer is further arranged in the anoxic zone, and a blade of the anoxic stirrer is positioned in the anoxic sludge.

In one embodiment of the present invention, the filling rate of the filler located at the upper part of the IFAS zone is 20% to 50%, preferably 20% to 35%, which can be adjusted according to the water quality.

In one embodiment of the invention, the packing in the upper portion of the IFAS zone is selected to be either fixed packing or floating packing, and when floating packing is used, a perforated baffle is provided in the middle of the IFAS zone to control the floating area of the packing.

In one embodiment of the present invention, the filler located in the upper part of the IFAS region is selected from polyurethane blocks, elastomeric fillers, plastic fillers or a combination of the different fillers mentioned above.

In one embodiment of the invention, the IFAS zone has a reactor aspect ratio in the range of 1: 1-1, preferably 1-1.

In one embodiment of the invention, the aeration means is located at the bottom of the IFAS zone.

In one embodiment of the present invention, the aeration device is a row of aeration tubes. Aeration can be carried out by selecting aeration discs, perforations, micropores and other modes according to suspension conditions.

In one embodiment of the invention, the aeration device is connected to a blower via an air conduit.

In one embodiment of the invention, the air pipeline is provided with an aeration valve, and the aeration valve is used for controlling aeration conditions.

In one embodiment of the invention, the aerobic sludge is present predominantly in the lower region of the IFAS zone.

In one embodiment of the invention, the area of the IFAS zone where the aerobic sludge is located is provided with a DO detector.

In one embodiment of the invention, the upper end of the central cartridge receives the wastewater treated by the IFAS zone via a conduit.

In one embodiment of the invention, a gap is formed between the reflecting plate and the lower end of the central cylinder, and sewage passes through the central cylinder and then is impacted by the reflecting plate to separate mud from water.

In one embodiment of the invention, a mud storage hopper is further arranged below the reflecting plate. Optionally, the horizontal angle of the mud storage hopper is 55 °.

In one embodiment of the present invention, in the IFAS sewage treatment plant of the present invention, the anoxic zone, the IFAS zone and the settling zone may be adjacently disposed and connected together, or may be separately disposed and connected therebetween by a pipeline. The apparatus may be designed as an integrated device or as a plurality of devices connected in series.

In one embodiment of the invention, the anoxic zone, the IFAS zone or the precipitation zone may be circular or rectangular in cross-section.

In one embodiment of the present invention, the anoxic zone, the IFAS zone, or the precipitation zone is made of glass fiber reinforced plastic, PVC, stainless steel, carbon steel, or the like.

In one embodiment of the present invention, the IFAS zone may be provided with a group of reactors combining upper fixed membrane and lower activated sludge, or may be provided with a plurality of groups of upper fixed membrane and lower activated sludge reactors according to the effluent quality, but preferably the number of the groups is not more than 4.

The invention also provides a treatment process for water treatment by the IFAS sewage treatment device based on the upper fixed membrane, which comprises an anoxic process performed in an anoxic zone, an anoxic process, an aerobic process, a short-cut nitrification and denitrification process and a synchronous nitrification and denitrification process performed in the IFAS zone, and a precipitation process performed in a precipitation zone.

An oxygen-deficient process: sewage and return sludge enter an anoxic zone through a return water inlet tank respectively, the sewage is fully contacted with the anoxic sludge in the anoxic zone under the stirring action of an anoxic stirrer, denitrifying bacteria in the anoxic sludge can utilize carbon-containing organic matters in the sewage as a carbon source to reduce nitrate radicals and nitrite radicals in return sludge liquid in a settling zone into nitrogen gas to be released, and partial denitrification is completed;

an aerobic process: the sewage treated by the anoxic zone enters the bottom of the IFAS zone through a pipeline, and the aeration of the aeration device is utilized to fully mix the sewage in the IFAS zone with aerobic sludge at the bottom of the IFAS zone; keeping DO level at the bottom of the IFAS zone to be 1.0 +/-0.3 mg/L; in the low DO state, a very small amount of aerobic reaction occurs in the aerobic sludge, and a part of microorganisms realize a micro growth process by utilizing dissolved oxygen and carbon-containing organic matters; compared with the conventional process, the yield of excess sludge is reduced;

the short-cut nitrification and denitrification process comprises the following steps: the sewage treated by the anoxic zone enters the bottom of the IFAS zone through a pipeline, and the sewage in the IFAS zone is fully mixed with aerobic sludge at the bottom of the IFAS zone by utilizing the aeration of the aeration device; keeping DO at the bottom of the IFAS area at 1.0 +/-0.3 mg/L; under the low DO state, the utilization rate of the carbon-containing organic matters is reduced, the proportion of the organic matters for biological denitrification is ensured, the low DO state can also influence the activity of nitrifying bacteria, weaken the nitrification process, keep the nitrosation process, improve the biological population advantage of nitrosation related strains, complete sludge domestication, realize short-cut nitrification, and further reduce the ammonia nitrogen concentration; the denitrification process of the sewage is carried out on the upper part of the IFAS area, microorganisms in the inner layer of the fixed membrane utilize the mass transfer influence of the biological membrane, carbon-containing organic matters in the sewage are utilized to reduce nitrite nitrogen into nitrogen to be released under the condition of lower dissolved oxygen, the process is completed for multiple times in the IFAS reactors connected in series to realize the removal of the organic matters and nitrogen in the sewage, and the area acclimates activated sludge through lower dissolved oxygen level to generate a short-range nitrification-denitrification process, thereby realizing the reasonable distribution and utilization of the carbon-containing organic matters in the sewage, solving the problem of too low C/N of the sewage and needing no additional carbon source regulation and control;

the synchronous nitrification and denitrification process comprises the following steps: the sewage treated by the anoxic zone enters the bottom of the IFAS zone through a pipeline, and the sewage in the IFAS zone and aerobic sludge at the bottom of the IFAS zone are fully mixed by utilizing the aeration of an aeration device and then reach the upper part of the IFAS zone; the DO of the IFAS bottom aeration zone is controlled to be 1.0 +/-0.3 mg/L, after the consumption of an aerobic process and a short-range nitrification process, the dissolved oxygen level of the upper fixed membrane zone of the IFAS zone is further reduced, microorganisms are nitrified on the surface of a biological membrane of a fixed filler under the condition of low dissolved oxygen, and due to the fact that the content of the dissolved oxygen is too low, and the mass transfer influence generated by the thickness of the biological membrane is combined, the inner layer of the biological membrane generates a more anoxic environment, a proper dissolved oxygen environment is provided for denitrification, and finally nitrification and denitrification synchronously occur on the outer layer and the inner layer of the biological membrane, so that the denitrification process is realized.

A precipitation process: and the sewage treated in the IFAS zone passes through the central cylinder and then is impacted by the reflecting plate to separate mud from water, the water after mud-water separation flows out of the water outlet tank, and the sludge generated in the settling zone flows back to the anoxic zone through the reflux pump and the sludge reflux pipe, so that the sludge reflux process is realized.

In one embodiment of the present invention, the IFAS zone may be aerated continuously or intermittently, the period of intermittent aeration may be adjusted within 15 to 120 minutes, and the ratio of aeration time to intermittent time may be adjusted from 2.

In one embodiment of the invention, the dissolved oxygen level in the IFAS zone is controlled within the range of 0.3-1.5 mg/L, and is adjusted according to the water quality condition of the effluent.

In one embodiment of the invention, the sludge reflux ratio is adjusted to be between 30 and 100 percent according to the sludge growth condition in the IFAS area.

Compared with the prior art, the invention has the advantages that:

according to the invention, the reaction zone is operated in a low dissolved oxygen state by regulating and controlling the integral dissolved oxygen level of the aeration section, so that the short-cut nitrification and denitrification process is enhanced; and by the design of the lower layer of activated sludge and the upper layer of fixed membrane, the synchronous nitrification and denitrification are realized in the upper layer of fixed membrane area by utilizing the mass transfer effect. The invention reduces aeration quantity and saves energy consumption; the utilization efficiency of the reactor space is improved, so that the required reactor volume under the same treatment scale is smaller, and the land resource is saved; meanwhile, on the premise of not coupling excessive processes and not adding an external carbon source, the denitrification potential of the IFAS device is further developed, the treatment of the low C/N sewage is completed, and the requirements on management and maintenance are lowered.

The IFAS device developed by the invention is used as a coupling device of activated sludge and a biological membrane, has extremely high potential in device optimization, develops the configuration potential of the IFAS device, and provides a new thought and a new method for treating sewage in villages and small towns.

Drawings

FIG. 1 is a schematic front view showing the structure of an IFAS sewage treatment apparatus having an upper fixed membrane according to example 1 of the present invention;

FIG. 2 is a schematic top view of an IFAS sewage treatment plant with an upper fixed membrane according to example 1 of the present invention.

The reference numbers in the figures indicate:

1. an anoxic zone; 2. an IFAS area; 3. a settling zone; 11. a water inlet tank is refluxed; 12. an anoxic stirrer; 13. a filler; 14. an air duct; 15. an aeration valve; 16. a DO detector; 17. a central barrel; 18. a water outlet groove; 19. a sludge return pipe; 20. anoxic sludge; 21. an aeration device; 22. aerobic sludge; 23. a reflective plate; 24. a reflux pump; 25. a blower.

Detailed Description

The invention is described in detail below with reference to the figures and the specific embodiments.

Examples

Referring to fig. 1 and fig. 2, the present embodiment provides an IFAS sewage treatment device with an upper fixed film, including an anoxic zone 1, an IFAS zone 2 and a sedimentation zone 3 which are communicated with each other by a pipeline, wherein anoxic sludge 20 is disposed in the anoxic zone 1, the anoxic zone 1 is used for receiving sewage to be treated, aerobic sludge 22 is disposed in the IFAS zone 2, an aeration device 21 is disposed in the aerobic sludge 22, a filler 13 is disposed on the upper portion of the aerobic sludge 22, the filler 13 forms an upper fixed film, and the bottom of the IFAS zone 2 is used for receiving sewage treated by the anoxic zone 1; the settling zone 3 is provided with a central cylinder 17, a water outlet tank 18 and a reflecting plate 23, the central cylinder 17 is used for receiving sewage treated by the IFAS zone 2, the reflecting plate 23 is arranged below the central cylinder 17 and used for distributing water uniformly and separating mud and water, and the water outlet tank 18 is arranged above the settling zone 3 and used for discharging water.

In this embodiment, the sludge generated in the settling zone 3 is returned to the anoxic zone 1 through the return pump 24 and the sludge return pipe 19, so as to realize the sludge return process. And a backflow water inlet groove 11 for receiving sewage and backflow sludge is formed in the upper part of the anoxic zone 1. An anoxic stirrer 12 is further arranged in the anoxic zone 1, and blades of the anoxic stirrer 12 are positioned in anoxic sludge 20.

In this embodiment, the filling rate of the filler 13 located at the upper part of the IFAS zone 2 is 20% to 50%, preferably 20% to 35%, which can be adjusted according to the water quality. The packing 13 located in the upper part of the IFAS zone 2 is selected to be either fixed packing or floating packing, and when floating packing is used, a perforated baffle is provided in the middle of the IFAS zone to control the floating area of the packing. The filler 13 located in the upper part of the IFAS zone 2 is selected from the group consisting of polyurethane blocks, elastomeric fillers, plastic fillers or a combination of the different fillers mentioned above.

In this embodiment, the aeration means 21 is located at the bottom of the IFAS zone 2. The aeration device 21 is a row of aeration pipes. Aeration can be carried out by selecting aeration discs, perforations, micropores and other modes according to suspension conditions. The aeration device 21 is connected to a blower 25 through an air pipe 14. An aeration valve 15 is arranged on the air pipeline 14, and the aeration valve 15 is used for controlling the aeration condition. The aerobic sludge 22 is mainly present in the lower region of the IFAS zone 2. And a DO detector 16 is arranged in the area of the aerobic sludge 22 in the IFAS area 2.

In this embodiment, the upper end of the central cartridge 17 receives via tubing the effluent being treated by the IFAS zone 2. A gap is formed between the reflecting plate 23 and the lower end of the central cylinder 17, and sewage passes through the central cylinder 17 and then is impacted by the reflecting plate 23 to separate mud from water. A mud storage hopper is also arranged below the reflecting plate 23. Optionally, the horizontal included angle of the mud storage hopper is 55 degrees.

In this embodiment, in the IFAS sewage treatment plant of the upper fixed membrane of the present invention, the anoxic zone 1, the IFAS zone 2 and the settling zone 3 may be adjacently disposed and connected together, or may be separately disposed and connected therebetween by a pipeline. The apparatus may be designed as an integrated device or as a series of multiple devices.

In this embodiment, the anoxic zone 1, the IFAS zone 2 or the precipitation zone 3 may be circular or rectangular in cross-section. In this embodiment, the anoxic zone 1, the IFAS zone 2, or the precipitation zone 3 are made of glass fiber reinforced plastics, PVC, stainless steel, carbon steel, or the like.

In this embodiment, the IFAS zone 2 may be provided with a group of reactors combining upper fixed membrane and lower activated sludge, or may be provided with a plurality of groups of upper fixed membrane and lower activated sludge reactors according to the quality of the effluent, but the number of the groups preferably does not exceed 4.

The embodiment also provides a treatment process for water treatment by the IFAS sewage treatment device based on the upper fixed membrane, which comprises an anoxic process performed in the anoxic zone 1, an anoxic process, an aerobic process, a short-cut nitrification and denitrification process and a synchronous nitrification and denitrification process performed in the IFAS zone 2, and a sedimentation process performed in the sedimentation zone 3.

An oxygen-deficient process: sewage and return sludge respectively enter the anoxic zone 1 through the return water inlet tank 11, under the stirring action of the anoxic stirrer 12, the sewage is fully contacted with anoxic sludge 20 in the anoxic zone 1, denitrifying bacteria in the anoxic sludge 20 can utilize carbon-containing organic matters in the sewage as carbon sources, nitrate radicals and nitrite radicals in return sludge liquid in the settling zone are reduced into nitrogen gas to be released, and partial denitrification is completed;

an aerobic process: the sewage treated by the anoxic zone 1 enters the bottom of the IFAS zone 2 through a pipeline, and the sewage in the IFAS zone 2 is fully mixed with aerobic sludge 22 at the bottom of the IFAS zone 2 by utilizing the aeration of an aeration device 21; keeping the DO level at the bottom of the IFAS area 2 at 1.0 +/-0.3 mg/L; in the low DO state, a very small amount of aerobic reaction occurs in the aerobic sludge 22, and a part of microorganisms realize a micro growth process by utilizing dissolved oxygen and carbon-containing organic matters; compared with the conventional process, the yield of the excess sludge is reduced;

the short-cut nitrification and denitrification process comprises the following steps: the sewage treated by the anoxic zone 1 enters the bottom of the IFAS zone 2 through a pipeline, and the sewage in the IFAS zone 2 is fully mixed with aerobic sludge 22 at the bottom of the IFAS zone 2 by utilizing the aeration of an aeration device 21; keeping DO at the bottom of the IFAS area at 1.0 +/-0.3 mg/L; under the low DO state, the utilization rate of the carbon-containing organic matters is reduced, the proportion of the organic matters for biological denitrification is ensured, the low DO state can also influence the activity of nitrifying bacteria, weaken the nitrifying process, keep the nitrosation process, improve the biological population advantages of nitrosation-related strains, complete sludge domestication and realize short-cut nitrification, thereby reducing the ammonia nitrogen concentration; the denitrification process of the sewage is carried out on the upper part of the IFAS area, microorganisms in the inner layer of the fixed membrane reduce nitrite nitrogen into nitrogen gas to be released by utilizing mass transfer influence of the biological membrane under the condition of lower dissolved oxygen, the removal of organic matters and nitrogen in the sewage is realized by completing the process for many times in the IFAS reactors connected in series, the area domesticates active sludge by lower dissolved oxygen level to generate a short-cut nitrification and denitrification process, the reasonable distribution and utilization of the carbon-containing organic matters in the sewage are realized, the problem of too low C/N of the sewage is solved, and no additional carbon source regulation is needed;

the synchronous nitrification and denitrification process comprises the following steps: the sewage treated by the anoxic zone 1 enters the bottom of the IFAS zone 2 through a pipeline, and the sewage in the IFAS zone 2 and aerobic sludge 22 at the bottom of the IFAS zone 2 are fully mixed by utilizing the aeration of an aeration device 21 and then reach the upper part of the IFAS zone 2; DO of an IFAS bottom aeration zone is controlled to be 1.0 +/-0.3 mg/L, after the consumption of an aerobic process and a short-range nitrification process, the dissolved oxygen level of an upper fixed membrane area of an IFAS zone 2 is further reduced, microorganisms are nitrified on the surface of a biological membrane of a fixed filler under the condition of low dissolved oxygen, and due to the fact that the content of the dissolved oxygen is too low, and the mass transfer influence generated by the thickness of the biological membrane is combined, the inner layer of the biological membrane generates a more anoxic environment, a proper dissolved oxygen environment is provided for denitrification, and finally nitrification and denitrification synchronously occur on the outer layer and the inner layer of the biological membrane, so that the denitrification process is realized.

A precipitation process: the sewage treated by the IFAS zone 2 passes through the central cylinder 17 and then is impacted by the reflecting plate 23 to separate mud from water, the water after mud and water separation flows out of the water outlet tank 18, and the sludge generated in the settling zone 3 flows back to the anoxic zone 1 through the reflux pump 24 and the sludge reflux pipe 19, so that the sludge reflux process is realized.

In this embodiment, the IFAS zone 2 may be aerated continuously or intermittently, the period of intermittent aeration may be adjusted within 15 to 120 minutes, and the ratio of aeration time to intermittent time may be adjusted from 2. The dissolved oxygen level of the IFAS zone 2 is controlled within the range of 0.3-1.5 mg/L and is adjusted according to the water quality condition of the effluent.

In this embodiment, the IFAS zone 2 reactor diameter to depth ratio can be adjusted according to the design dissolved oxygen conditions and packing. The adjustment range is 1.

The sludge reflux ratio is adjusted to 30-100% according to the sludge growth condition in the IFAS area.

The embodiments described above are intended to facilitate a person of ordinary skill in the art in understanding and using the invention. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims

1. An IFAS sewage treatment device with an upper fixed membrane is characterized by comprising an anoxic zone (1), an IFAS zone (2) and a sedimentation zone (3) which are communicated through a pipeline, wherein anoxic sludge (20) is arranged in the anoxic zone (1), the anoxic zone (1) is used for receiving sewage to be treated,

aerobic sludge (22) is arranged in the IFAS zone (2), the aerobic sludge mainly exists in the lower area of the IFAS zone, an aeration device (21) is arranged in the aerobic sludge (22), a filler (13) is arranged at the upper part of the aerobic sludge (22), the filler (13) forms an upper fixed film, and the bottom of the IFAS zone (2) is used for receiving sewage treated by the anoxic zone (1);

the IFAS area (2) is provided with a group of reactors combining an upper fixed membrane and a lower activated sludge, or is provided with no more than 4 groups of reactors combining an upper fixed membrane and a lower activated sludge according to the quality of effluent;

the settling zone (3) is provided with a central cylinder (17), a water outlet groove (18) and a reflecting plate (23), the central cylinder (17) is used for receiving sewage treated by the IFAS zone (2), the reflecting plate (23) is arranged below the central cylinder (17) and used for uniformly distributing water and separating mud and water, and the water outlet groove (18) is arranged above the settling zone (3) and used for discharging water;

controlling DO of an aeration zone at the bottom of the IFAS to be 1.0 +/-0.3 mg/L;

the IFAS zone (2) is subjected to short-cut nitrification and denitrification and synchronous nitrification and denitrification reactions.

2. The IFAS sewage treatment plant of the upper fixed membrane according to claim 1, wherein the sludge generated in the settling zone (3) is returned to the anoxic zone (1) through a return pump (24) and a sludge return pipe (19) to realize a sludge return process.

3. The IFAS sewage treatment plant of the upper fixed membrane according to claim 1, wherein an anoxic stirrer (12) is further arranged in the anoxic zone (1), and a blade of the anoxic stirrer (12) is positioned in the anoxic sludge (20).

4. The IFAS sewage treatment plant with the upper fixed membrane as claimed in claim 1, wherein the filling rate of the filler (13) at the upper part of the IFAS zone (2) is 20% -50%;

the packing (13) located in the upper part of the IFAS zone (2) is selected to be fixed packing or suspended packing, and when suspended packing is used, a perforated partition is arranged in the middle of the IFAS zone to control the suspended area of the packing.

5. An IFAS effluent treatment plant as claimed in claim 1 wherein said aeration means (21) is located at the base of said IFAS zone (2);

the aeration device (21) is connected with a blower (25) through an air pipeline (14);

an aeration valve (15) is arranged on the air pipeline (14), and the aeration valve (15) is used for controlling the aeration condition.

6. The IFAS sewage treatment plant of claim 1, wherein the area of the IFAS zone (2) where the aerobic sludge (22) is located is provided with a DO detector (16).

7. The IFAS sewage treatment plant based on the upper fixed membrane as defined in any one of claims 1 to 6, wherein the treatment process comprises an anoxic process performed in the anoxic zone (1), an anoxic process, an aerobic process, a short-cut nitrification and denitrification process, and a simultaneous nitrification and denitrification process performed in the IFAS zone (2), and a sedimentation process performed in the sedimentation zone (3).

8. The treatment process according to claim 7,

an oxygen-deficient process: sewage and return sludge respectively enter the anoxic zone (1) through the return water inlet tank (11), under the stirring action of the anoxic stirrer (12), the sewage is fully contacted with anoxic sludge (20) in the anoxic zone (1), denitrifying bacteria in the anoxic sludge (20) utilize carbon-containing organic matters in the sewage as carbon sources, nitrate radicals and nitrite radicals in return sludge liquid in the settling zone are reduced into nitrogen gas to be released, and partial denitrification is completed;

an aerobic process: the sewage treated by the anoxic zone (1) enters the bottom of the IFAS zone (2) through a pipeline, and the sewage in the IFAS zone (2) is fully mixed with aerobic sludge (22) at the bottom of the IFAS zone (2) by utilizing the aeration of an aeration device (21); keeping the DO level at the bottom of the IFAS area (2) at 1.0 +/-0.3 mg/L; a very small amount of aerobic reaction occurs in the aerobic sludge (22), and a part of microorganisms realize a micro growth process by utilizing dissolved oxygen and carbon-containing organic matters;

the short-cut nitrification and denitrification process comprises the following steps: the sewage treated by the anoxic zone (1) enters the bottom of the IFAS zone (2) through a pipeline, and the sewage in the IFAS zone (2) is fully mixed with aerobic sludge (22) at the bottom of the IFAS zone (2) by utilizing the aeration of an aeration device (21); keeping DO at the bottom of the IFAS area at 1.0 +/-0.3 mg/L; under the low DO state, the utilization rate of the carbon-containing organic matters is reduced, the proportion of the organic matters for biological denitrification is ensured, the low DO state can also influence the activity of nitrifying bacteria, weaken the nitrifying process, keep the nitrosation process, improve the biological population advantages of nitrosation-related strains, complete sludge domestication and realize short-cut nitrification, thereby reducing the ammonia nitrogen concentration; the denitrification process of the sewage is carried out on the upper part of the IFAS area, the microorganisms in the inner layer of the fixed membrane utilize the mass transfer influence of the biological membrane, the carbon-containing organic matters in the sewage are utilized to reduce the nitrite nitrogen into nitrogen and release the nitrogen under the condition of lower dissolved oxygen, the process is completed for many times in the IFAS reactors connected in series, the removal of the organic matters and the nitrogen in the sewage is realized, and the area domesticates the activated sludge through lower dissolved oxygen level to generate the short-cut nitrification and denitrification process, so that the reasonable distribution and utilization of the carbon-containing organic matters in the sewage are realized;

the synchronous nitrification and denitrification process comprises the following steps: the sewage treated by the anoxic zone (1) enters the bottom of the IFAS zone (2) through a pipeline, and the sewage in the IFAS zone (2) and aerobic sludge (22) at the bottom of the IFAS zone (2) are fully mixed by utilizing the aeration of an aeration device (21) and then reach the upper part of the IFAS zone (2); DO of an aeration zone at the bottom of the IFAS is controlled to be 1.0 +/-0.3 mg/L, after the consumption of an aerobic process and a short-range nitrification process, the dissolved oxygen level of a fixed membrane zone at the upper part of the IFAS zone (2) is further reduced, microorganisms utilize ammonia nitrogen in sewage to carry out nitrification on the surface of a biomembrane of a fixed filler, so that a more anoxic environment is generated on the inner layer of the biomembrane, a proper dissolved oxygen environment is provided for denitrification, and finally nitrification and denitrification synchronously occur on the outer layer and the inner layer of the biomembrane to realize the denitrification process;

a precipitation process: the sewage treated by the IFAS area (2) passes through the central cylinder (17) and then is impacted by the reflecting plate (23) to separate mud and water, the water after mud and water separation flows out of the water outlet groove (18), and the sludge generated in the settling area (3) returns to the anoxic area (1) through the reflux pump (24) and the sludge reflux pipe (19), so that the sludge reflux process is realized.

9. The process according to claim 8, characterized in that the IFAS zone (2) is aerated continuously or intermittently, the period of intermittent aeration is adjusted within 15 to 120 minutes, and the ratio of aeration time to intermittent time is adjusted from 2 to 1;

the dissolved oxygen level of the IFAS area (2) is controlled within the range of 0.3 to 1.5 mg/L;

the sludge reflux ratio is between 30 and 100 percent;

the diameter-depth ratio of the IFAS zone (2) reactor can be adjusted within the range of 1 to 1.